Besides the aesthetics, it will come down to the characteristics of the knot. I think from your other thread you should have a pretty good idea of what to expect out of the XLs. They are a known quantity.
The LEs (I assume you mean the Finest badger ones) are more of a mystery since they have not hit the market yet, but the properties of their hair should be within a reasonable distance of Semogue's standard Finest bristle. It is well regarded, but does contain some scritch, if that is your cup of tea.
Oh, and the LEs are 24/25mm, whereas the XLs can go significantly BIGGER than that (28 and 30mm).
When faced with this dilema I was decisive and answered BOTH.
Besides size, I expect the tips on the Semogue LEs to be a little scritchier (if they are like my Semogue SOC 2-band) than the freakishly soft Heritage XL hair.
What brushes do you currently own? Do you like to face or bowl lather? Do you like some scritch? Do you want a brush to round out what you have or one that is similar to what you have?
I love my 1XL & 2XL, but I'm also really impressed with my Semogue Caravela, which led me to order both a Semogue LE 2011 Finest Badger size 2 and a Finest Bristle size 1.
How do they compare to the Rooneys????